The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
An increased focus on extending and optimizing the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) Release 8 radio access technologies for providing higher data rates cost-effectively exists. An improved version of the Long Term Evolution radio access system is called LTE-Advanced (LTE-A). The main target of the 3GPP project is to improve the Universal Mobile Telecommunications System (UMTS) mobile phone standard for providing an enhanced user experience and simplified technology for next generation mobile broadband. The LTE is designed to support high-speed data, multimedia unicast and multimedia broadcast services.
Typically, higher data rates also set increased requirements for control signaling. Uplink control signals, such as Acknowledgement (ACK), Negative Acknowledgement (NACK), Channel Quality Indicator (CQI), and uplink scheduling requests may be transmitted on a Physical Uplink Control Channel (PUCCH) in the absence of uplink data.
In LTE, PUCCH Format 2 is designed to convey periodic CQI, Precoding Matrix Indicator (PMI) and Rank Indicator (RI). Control signaling in PUCCH is based on sequence modulation. Cyclically shifted zero-autocorrelation sequences take care of both code-division multiple access between user devices and the conveyance of the control information. On the PUCCH Format 2 zero-autocorrelation sequences of length 12 symbols (1 resource block) are Quadrature Phase Shift keying (QPSK) modulated thus carrying two information bits per sequence. Different user devices may be multiplexed by using different cyclic shifts of a zero-autocorrelation sequence into the given frequency/time resource. Typically, six parallel channels per a Resource Block (RB) are provided, assuming that an every second cyclic shift is in use.